The period of a body under SHM is represented by T=PaDbSc,
where P is pressure, D is density and S is surface tension.
The value of a, b and c are:
By substituting the dimension of each quantity,
we get
T=
=[ML−1T−2]a[L−3M]b[MT−2]c
Now comparing the dimenstions of quantities in both sides,
we get a+b+c=0, −a−3b=0
and −2a−2c=1
∴x=−12,
y=12.